1. Field of the Invention
This invention relates to a collision determination device, a collision determination method, and an occupant protection device. More particularly, this invention relates to a collision determination device, collision determination method, and occupant protection device that reliably determine the occurrence of a collision against a door part from the outside and prevent erroneous determination on the occurrence of a collision against the door part from the outside.
2. Description of the Related Art
In recent years, there has been proposed an occupant crash protection device for vehicles which determines occurrence of a collision against a door part of a vehicle from the outside and actuates a side airbag upon a determination that a collision has occurred, to protect an occupant (see Japanese Patent Application Publication No. 2007-137332 (JP-A-2007-137332), for example). This occupant crash protection device for vehicle determines that a collision has occurred against the door part of the vehicle from the outside, when a pressure sensor provided on the door part of the vehicle detects a change in pressure inside the door part.
However, although the above-described occupant crash protection device for vehicle detects a change in pressure inside the door part that is deformed due to the collision from the outside, the occupant crash protection device cannot detect a change in pressure if the outside collision does not deform the door part. For this reason, collision determination cannot be performed reliably.
Therefore, a technology that is capable of determining the occurrence of a collision even when the outside collision does not deform the door part is available (see Published Japanese Translation of PCT Application No. 2007-510134 (JP-A-2007-510134), for example). According to this technology, when an acceleration sensor integrated with a door part of a vehicle detects an acceleration that is equal to or greater than an acceleration generated by opening and closing the door part, it is determined that a collision has occurred against the door part of the vehicle from the outside.
However, when the door part is closed with strong force, the above-described technology detects the acceleration that is equal to or greater than an acceleration generated by opening and closing the door part. Therefore, this technology erroneously determines the occurrence of a collision against the door part from the outside, even when the door part was simply closed with strong force. As a result, the side airbag is actuated erroneously.